Measurement of vertical liquid water path by means of an airborne radiometer and the shortwave albedo of marine low-level clouds during WENPEX in Japan

The result of the air truth of the LWP_radiometer indicates that the 37-GHz microwave radiometer gives an estimation of the LWP accurate to 100 mg cm^-2. The shortwave cloud albedo was related to the LWP_radiometer. The albedo increases with the LWP, independent of cloud type, when measured just above the cloud tops. The measured albedo is nearly the same as the calculated albedo when the LWP_radiometer is larger than 60 mg cm^-2 but much smaller than the calculated albedo when the LWP_radiometer is less than 40 mg cm^-2. Cloud-top irregularity is suggested to be the primary cause of this discrepancy. The degree of inhomogeneity of the horizontal distribution of liquid water appears to be correlated with the amount of precipitable water in the planetary boundary layer. -from Authors